Pull type harvesting machines are towed from the tractor by a hitch arm which requires to be adjusted in angle relative to the frame of the machine for fine steering movements and more coarse movement to the transport position.
Some machines are required to follow the tractor only to one side and thus include a hitch arm which is located at one end of the machine. In others in which the present invention is particularly effective, the hitch arm to the tractor extends from the frame over the header to a hitch coupling and can be swung by an operating cylinder from one side of the header to the other so that the header can be located in echelon with the tractor to one side of symmetrically to the other side.
Pull-type harvesting machines of this type are well known and there are many different examples manufactured by a number of different companies. One problem which has arisen with many different designs is that of controlling the movement of the machine from one side of the tractor to the other side of the tractor. It will be appreciated that the machine applies significant loads to the hitch arm from the significant amount of weight which is moved across behind the tractor by actuating a cylinder which pushes the hitch arm to one side or the other as required to transfer the machine to the required echelon position. Conventionally heavy stops are provided on the mechanical elements, that is on the frame or the hitch arm or on both so as to locate the machine at the required position. As the machine moves across, impact on this stop can incur significant forces against the stop so that the mechanical elements involved must be built with these forces in mind and thus must be stronger than might otherwise be required.
In addition it is desirable that there be provided an ability to adjust the stop member so that the echelon position can be accurately located. If the stop is incorrectly positioned, the header may be located either too far away from the tractor, in which case a strip of crop material may be missed during the harvesting action or to close to the tractor, in which case the maximum operating width of the header is not fully utilized. If either of these conditions occurs, it is necessary for operator to steer the machine by moving the cylinder away from the end stop. This is tiring for the operator and causes the machine to return the end stop more frequently with the possibility of further damage.